Field of the Invention
The present invention relates t o a camera control system arranged to capture a video signal from an image pickup apparatus and distribute the video signal to clients through a network, and also relates to matters concerned with the camera control system.
Description of Related Art
There are known systems in which a video image obtained from a video camera connected to a network such as the Internet is rendered viewable at a number of remote places (clients). In some of such systems, the clients are enabled not only to view the video image from the video camera but also to remotely control the video camera in such a way as to vary its panning and tilting angles and its zoom magnification. For example, a camera control system has been developed by the assignee of the present invention, in which a video camera which is controllable by computers is connected to a server connected to a WWW (world wide web) of the Internet, a video image picked up by the video camera is distributed in real time to clients so as to display the video image, and in addition, the panning, tilting, zooming, etc., of the video camera are enabled to be controlled by the clients. In such a camera control system, only one of the clients is allowed to acquire a control right to control the video camera, so that only the client having acquired the control right can perform a camera control, such as panning and tilting of the video camera, at a time. Further, in the camera control system, if a plurality of clients wish to control the video camera, the clients wishing the camera control may be given the control right to the video camera one after another at intervals of a predetermined time.
However, with one video camera arranged to be accessible by a plurality of clients through a network, the above-stated arrangement for enabling only one client having the camera control right to control the video camera for panning or tilting in a desired direction or for serially shifting the camera control right from one client to another tends to make the video image extremely disagreeable to most of clients other than the client who is controlling the video camera. Therefore, in cases where a great number of clients are viewing a video image obtained from the video camera, the arrangement for granting the camera control right to a specific client or clients does not always give a good result.
Further, when the camera control right is shifted from one client to another, a video image picked up by the video camera as desired by many other clients might be suddenly changed over to another video image directed in a very different direction. Such a change is extremely disagreeable to the other clients viewing the video image.